I'm so SO sorry to hear that. I've lost most of my family to cancer as well (just me, my half-brother, and my wife left - she's lost her entire family to disease as well, and we almost lost her to stage III breast cancer - she is still burdened with that today), and I'm an ex-cop and ex-military - both careers familiar to loss of ones close to us. I understand the pain and anger that you've gone through, and still deal with on a daily - minute-by-minute basis. All I can offer you is a reiteration of what you've already said, that music can help heal. Or at least help deal.
Fortunately (for both you and I) the bass guitar is a very ~physical~ instrument, and playing it can really help release feeling of unfairness, anger, bitterness, and hopeless dispair. It is - as people like us already know - absolutely necessary to release that black mojo, otherwise it will end up killing us as well.
I can only offer some hope that you and dad are able to cope with the severe - deep - losses and learn to use what has been taken from you to better ends. I know that sounds cliche as all hell, but there is little else I can tell you that will actually mean anything solid. Having walked that same path, I know that "words" from others - while well-intended - don't mean much. Just know that there is another person on the other side of Planet Earth that is dealing with heavy losses as well. And maybe I'll think of you as an inspiration to remind me that others have known heavy losses, as well as I have. I hope that perhaps you may find some tiny bit of solace knowing the same about me.
All we can do is offer mutual condolences and reassure one another that we're both doing our damnedest to get through each minute of each day.
And just because there is this odd cosmic/karmic connection between us, I WILL fetch Clockwork Angels, if nothing else but to draw strength from it knowing that another person around the world told me that it would help, and that other person lives in the same place as I do (so to speak).
And so there is the shove I needed. Thank you Cronkers. Be well, keep your strength, we'll both attempt to remind ourselves that we will do our best to live each day to it's fullest and not succumb to the lows thrown in our laps.
We owe at least that much to those we've survived. Good on ya for taking that attitude.